/*
 * TeXTokenMarker.java - TeX/LaTeX/AMS-TeX token marker
 * Copyright (C) 1998 Slava Pestov
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */

package org.syntax.jedit.tokenmarker;

import javax.swing.text.Segment;

/**
 * TeX token marker.
 * 
 * @author Slava Pestov
 * @version $Id: TeXTokenMarker.java,v 1.16 1999/12/13 03:40:30 sp Exp $
 */
public class TeXTokenMarker extends TokenMarker
{
    // public members
    public static final byte BDFORMULA = Token.INTERNAL_FIRST;

    public static final byte EDFORMULA = (byte) (Token.INTERNAL_FIRST + 1);

    public byte markTokensImpl(byte token, Segment line, int lineIndex)
    {
        char[] array = line.array;
        int offset = line.offset;
        int lastOffset = offset;
        int length = line.count + offset;
        boolean backslash = false;
        loop: for (int i = offset; i < length; i++)
        {
            int i1 = (i + 1);

            char c = array[i];
            // if a backslash is followed immediately
            // by a non-alpha character, the command at
            // the non-alpha char. If we have a backslash,
            // some text, and then a non-alpha char,
            // the command ends before the non-alpha char.
            if (Character.isLetter(c))
            {
                backslash = false;
            }
            else
            {
                if (backslash)
                {
                    // \<non alpha>
                    // we skip over this character,
                    // hence the `continue'
                    backslash = false;
                    if (token == Token.KEYWORD2 || token == EDFORMULA)
                        token = Token.KEYWORD2;
                    addToken(i1 - lastOffset, token);
                    lastOffset = i1;
                    if (token == Token.KEYWORD1)
                        token = Token.NULL;
                    continue;
                }
                else
                {
                    // \blah<non alpha>
                    // we leave the character in
                    // the stream, and it's not
                    // part of the command token
                    if (token == BDFORMULA || token == EDFORMULA)
                        token = Token.KEYWORD2;
                    addToken(i - lastOffset, token);
                    if (token == Token.KEYWORD1)
                        token = Token.NULL;
                    lastOffset = i;
                }
            }
            switch (c)
            {
            case '%':
                if (backslash)
                {
                    backslash = false;
                    break;
                }
                addToken(i - lastOffset, token);
                addToken(length - i, Token.COMMENT1);
                lastOffset = length;
                break loop;
            case '\\':
                backslash = true;
                if (token == Token.NULL)
                {
                    token = Token.KEYWORD1;
                    addToken(i - lastOffset, Token.NULL);
                    lastOffset = i;
                }
                break;
            case '$':
                backslash = false;
                if (token == Token.NULL) // singe $
                {
                    token = Token.KEYWORD2;
                    addToken(i - lastOffset, Token.NULL);
                    lastOffset = i;
                }
                else if (token == Token.KEYWORD1) // \...$
                {
                    token = Token.KEYWORD2;
                    addToken(i - lastOffset, Token.KEYWORD1);
                    lastOffset = i;
                }
                else if (token == Token.KEYWORD2) // $$aaa
                {
                    if (i - lastOffset == 1 && array[i - 1] == '$')
                    {
                        token = BDFORMULA;
                        break;
                    }
                    token = Token.NULL;
                    addToken(i1 - lastOffset, Token.KEYWORD2);
                    lastOffset = i1;
                }
                else if (token == BDFORMULA) // $$aaa$
                {
                    token = EDFORMULA;
                }
                else if (token == EDFORMULA) // $$aaa$$
                {
                    token = Token.NULL;
                    addToken(i1 - lastOffset, Token.KEYWORD2);
                    lastOffset = i1;
                }
                break;
            }
        }
        if (lastOffset != length)
            addToken(length - lastOffset, token == BDFORMULA || token == EDFORMULA ? Token.KEYWORD2 : token);
        return (token != Token.KEYWORD1 ? token : Token.NULL);
    }
}
